• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2504-2510
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• 2018

Actuator failures and the failures of controlled objects are often considered together. To overcome this limitation, a class of sliding mode observers for the fault diagnosis of nonlinear systems is designed in this paper. Due to the influence of the sliding mode function, the control strategy and the residual change of the observer exhibit certain trends governed by specific relations. Therefore, according to the changes in the control strategy and the observer residuals, the sensor and actuator faults in nonlinear systems can be determined. Finally, the effectiveness of the proposed method is verified based on simulations of a DC motor system.

• 전자공학회논문지A
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• 제30A권12호
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• pp.60-68
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• 1993

Thw VLSI device of submicron level trends to have a low level of reliability because of hot carriers which are caused by short channel effects and which do not appear in a long-channel MOSFET operated in 5V. In order to minimize the generation of hot carrier, much research has been made into various types of drain structures. This study has suggested CG MOSFET (Concaved Gate MOSFET) as new drain structure and compared its electrical characteristics with those of the conventional MOSFET and LDD-structured MOSFET by making use of a simulation method. These three device were assumed to be produced by the LOCOS process and a computer-based analysis(PISCES-2B simulator) was carried out to verify the hot electron-resistant behaviours of the devices. In the present simulation, the channel length of these devises was 1.0$\mu$m and their DC characteristics, such as VS1DT-IS1DT curves, gate and substrate current, potential contours, breakdown voltage and electric field were compared with one another.

• 한국자기학회지
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• 제12권1호
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• pp.20-23
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• 2002

CoCrPt 합금박막의 국소보자력 분포를 400nm공간분해능으로 8000개의 국소영역을 동시에 측정할 수 있는 광자기 현미경 자력계로 관찰하였다. 시료들은 dc 마그네트론 스퍼터링 방식으로 Pt 함량을 6 at.%에서 28 at.%로 변화시키며 제작되었다. Pt 함량이 증가함에 따라 ,국소보자력 분포가 정규분포에서 비정규분포로 변화하며 국소보자력 분포폭이 증가함을 발견하였다. 투과전자현미경으로 관찰한 미세구조를 분석한 결과는 국소보자력 분포 변화가 결정립의 크기 분포 및 평균크기 변화와 깊이 연관되어 있음을 나타내었다.

• 한국자원식물학회지
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• 제20권2호
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• pp.193-200
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• 2007

국내 분포하는 것으로 알려진 노루발과 7분류군의 화분에 대하여 분류학적 가치를 파악하기 위하여 광학현미경과 주사전자현미경으로 관찰하였다. 성숙한 화분의 단위(pollen unit)는 Pyrola속의 호노루발[P. dahurica(Andres) Kom.], 분홍노루발[P. incarnata(DC.) Fisch. ex Kom.], 노루발(P. japonica Klenze ex Alefeld), 주걱노루발(P. minor L.), 콩팥노루발(P. renifolia Max.)에서 사립(tetrad), Orthilia속의 새끼노루발[P. secunda(L.) House]에서 단립(monad), Chimaphila속의 매화노루발(C. japonica Miq.)에서 사립들이 엉성하게 모여 다립(polyad)을 형성하였다. 이와 같이 노루발과의 성숙한 화분의 단위는 과내 속을 구분하는 중요한 형질로 판단되었으며, 이를 근거로 새끼노루발의 학명은 Pyrola secunda L.보다는 Orthilia secunda(L.) House가 적합한 것으로 생각되었다. 화분의 크기와 삼공구형(tricolporate)인 발아구의 크기, 표벽 무늬는 분류군 간에 다소 차이를 나타냈으며, 호노루발과 콩팥노루발, 분홍노루발, 주걱노루발의 표면무늬는 기존 보고와 다소 상이하였다. 본 연구에서 취급된 분류군들의 화분은 성숙한 화분의 구성단위가 각기 사립에서 단립과 다립으로, 발아구의 형태가 공구형에서 공형으로의 진화경향성을 추론할 수 있었다.

• 한국음향학회지
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• 제39권2호
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• pp.113-119
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• 2020

자동차에서의 모터 사용 증가로 자동차 실내 음질(sound quality) 향상을 위해 모터 소음이 주요 관심사이다. 본 연구의 목적은 부하변화에 따른 모터 소음 성능을 나타낼 수 있는 인자를 제안하는 것이다. 이를 위하여, 파워스펙트럼과 라우드니스가 소음 성능을 나타내는데 적합하지 않음을 확인하였고, 브러쉬 마찰 성분과 관련된 부분라우드니스(PN_B)와 토크 리플 성분과 관련된 부분라우드니스(PN_R)가 소음 성능을 나타내는 인자로 파악되었다. 그리고 PN_B와 PN_R를 이용하여 부하에 따른 모터 소음의 변화 특성을 나타내기 위한 방법으로 모터 소음 성능 곡선을 제안하였다. 이 곡선은 소음 제어, 모터 선정 및 시스템 개선을 위한 가이드로 활용될 것으로 기대된다.

• Earthquakes and Structures
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• 제11권5호
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• pp.741-777
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• 2016

A simplified approach of assessing torsionally balanced (TB) and torsionally unbalanced (TU) low-medium rise buildings of up to 30 m in height is presented in this paper for regions of low-to-moderate seismicity. The Generalised Force Method of Analysis for TB buildings which is illustrated in the early part of the paper involves calculation of the deflection profile of the building in a 2D analysis in order that a capacity diagram can be constructed to intercept with the acceleration-displacement response spectrum diagram representing seismic actions. This approach of calculation on the planar model of a building which involves applying lateral forces to the building (waiving away the need of a dynamic analysis and yet obtaining similar results) has been adapted for determining the deflection behaviour of a TU building in the later part of the paper. Another key original contribution to knowledge is taking into account the strong dependence of the torsional response behaviour of the building on the periodic properties of the applied excitations in relation to the natural periods of vibration of the building. Many of the trends presented are not reflected in provisions of major codes of practices for the seismic design of buildings. The deflection behaviour of the building in response to displacement controlled (DC) excitations is in stark contrast to behaviour in acceleration controlled (AC), or velocity controlled (VC), conditions, and is much easier to generalise. Although DC conditions are rare with buildings not exceeding 30 m in height displacement estimates based on such conditions can be taken as upper bound estimates in order that a conservative prediction of the displacement profile at the edge of a TU building can be obtained conveniently by the use of a constant amplification factor to scale results from planar analysis.

• 한국자원식물학회지
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• 제16권1호
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• pp.89-98
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• 2003

본 연구에서는 Atractylodes속과 혼용되는 Atractylis속 6분류군의 화분을 광학현미경과 주사전자현미경으로 관찰하였다 본 속의 화분은 단립(monad)으로, 극축의 길이는 46.5-66.7$\mu\textrm{m}$, 적도면의 나비는 43.6-60.47$\mu\textrm{m}$이 었다. 발아구는 3공구형 (tri-colporate)으로서 , 구구(colpus)의 길이는 19.6-29.1 $\mu\textrm{m}$, 나비는 7.3-11.0$\mu\textrm{m}$이 었고, 공구의 직경 은 6.4-10.6$\mu\textrm{m}$ 이었다. 화분벽은 외표벽 (ektexine)은 기저층(foot layer)과 원주층(columellae), 피복층(tectum)으로 구성되고, 두에는 5.2-8.3$\mu\textrm{m}$이었다. 화분의 표면 돌기는 자상(echinate)으로서 길이가 1.4-5.8$\mu\textrm{m}$이었으며, 단위면적당(No./20$\mu\textrm{m}$$^2$) 분포는 6-33개 이었다 본 연구에서 취급된 분류군들의 화분, 특히 Atractylis arabica, A. aristata, A. carduus, A. microcephala의 화분형 태는 Atractylodes속의 화분과 매우 유사하였으며, 따라서 화분에 관련된 형질은 두 속을 구분하는 식별형질로 적용할 수 없었다. 그러나 화분에 관련된 형질이 Atractylodes속에서는 화분의 크기만이 속내 분류군간의 식별형질로서 기여도가 적은 반면, Atractylis속에서는 화분의 크기뿐만 아니라 형태 및 표면무늬와 자상돌기의 크기 등에 있어서 분류군간 의 식별형질로서 적용되어 분류학적 기여도가 다소 큰 것으로 판단된다. 또한 본 연구에서 취급된 분류군 중 A. cancellata와 A. prolifera는 나머지 분류군들과 달리 자상돌기가 작고 적도면상이 긴 특징은 본속의 화분의 진화경 향성을 파악하는데 매우 유용하였다.

• Journal of Power Electronics
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• 제18권5호
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• pp.1567-1576
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• 2018

The reliability of grid-connected inverters can be improved by algorithms capable of diagnosing faults in LCL filters. A fault diagnostic method during inverter startup is proposed. The proposed method can accurately generate and monitor information on the peak value and the location of the peak frequency component of the step response of a damped LCL filter. To identify faults, the proposed method compares the evaluated response with the response of a healthy higher-order damped LCL filter. The frequency components in the filter voltage response are first analytically obtained in closed form, which yields the expected trends for the filter faults. In the converter controller, the frequency components in the filter voltage response are computed using an appropriately designed fast Fourier transform and compared with healthy LCL response parameters using a finite state machine, which is used to sequence the proposed startup diagnostics. The performance of the proposed method is validated by comparing analytical results with the simulation and experimental results for a three-phase grid-connected inverter with a damped LCL filter.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.361-365
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• 2002

Advancements in silicon phase control (SCR) technologies provide an arc welding power supply that has the capability to allow the alteration of the Alternating Current (AC) welding output. These technologies provide a square wave output involving sixteen frequency selections and multiple balance selections. While an AC out put is known to minimize magnetic disturbances associate with Direct Current (DC), the potentials of a non-sinusoidal waveform have not been explored. The focus of the paper is to determine the effects that the frequency and balance of an AC wave form output will have upon a high speed Submerge Arc (SAW) application. The test matrix of the project includes welding .250" steel plate. Joint type is square groove with a travel speed of 65 IPM. Each of the weld parameters was held constant, only the frequency and/or balance were altered between welds. Each frequency/balance combination involved three-gap spacing. Upon completion of the welds the bead profiles were measured and recorded. A relationships/trends were observed with various frequency and balance values. Optimum frequency and balance values were found for the .250" square groove application which permit consistent weld sizing, ease of slag removal, and minimal plate distortion.

• 세라미스트
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• 제23권1호
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• pp.16-26
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• 2020

Recently, polymer-metal composite (IPMC)-based ionic artificial muscle has been drawing a huge attention for its excellent soft actuator performance having outstanding soft actuator performance with efficient conversion of electrical energy to mechanical energy under low working voltage. In addition, light, flexible and soft nature of IPMC and high bending strain response enabled development of versatile sensor application in association with soft actuator. In this paper, current issues of IPMC were discussed including standardizing preparation steps, relaxation under DC bias, inhibiting solvent evaporation, and improving poor output force. Solutions for these drawbacks of IPMC have recently been suggested in recent studies. After following explanation of the IPMC working mechanism, we investigate the main factors that affect the operating performance of the IPMC. Then, we reviewed the optimized IPMC actuator fabrication conditions especially for the preparation process, additive selection for a thicker membrane, water content, solvent substitutes, encapsulation, etc. Lastly, we considered the pros and cons of IPMCs for sensor application in a theoretical and experimental point of view. The strategies discussed in this paper to overcome such deficiencies of IPMCs are highly expected to provide a scope for IPMC utilization in soft robotics application.